1. Field of the Invention
The present invention relates in general to a reloadable lighttight plastic cassette for holding a roll of light-sensitive web material and for dispensing the web through a lighttight dispenser slot, and in particular to a cassette which is reloadable in daylight with a lighttightly packaged roll of light-sensitive material, and which is almost universally usable in existing apparatus that operate with so-called dedicated cassettes.
The invention also aims to provide a cassette that is made of plastics that are ecologically more interesting than PVC-type plastics, that up to now have and are being used on a large scale for the manufacture of the housing and/or side caps of suchlike cassettes.
2. Description of the Prior Art
Reloadable lighttight cassettes for holding a roll of light-sensitive web material and dispensing it through a lighttight slot are known, in particular in the field of phototypesetting. These cassettes are reloaded by the operator in the darkroom with a fresh roll of light-sensitive film or paper which is supplied by the manufacturer in a suitable lighttight wrapper and can then be placed in daylight in a phototypesetter apparatus where only the leader of the roll that serves for the engagement of the film by the transport rollers of the apparatus becomes exposed to actinic light before the apparatus is lighttightly closed.
The mentioned cassettes are dedicated or machine-type cassettes and are solid constructions usually made by injection-moulding of light metal, such as aluminium, or of high-grade plastics such as high impact polystyrene or ABS, and they form so to say part of the apparatus.
Since a phototypesetter apparatus usually operates with different widths and different types of light-sensitive material, it is clear that several cassettes have to be provided for each apparatus what raises the costprice of the installation.
The photographic industry has succeeded in avoiding the use of a darkroom by providing lighttightly packaged rolls of light-sensitive material in cheap disposable cassettes. These cassettes are made of cardboard, cheap plastic or a combination of both and have outer dimensions that are compatible with those of the original dedicated cassettes so that they can replace these cassettes on an almost universal scale.
Environmental considerations are putting an ever growing strain on the use of these disposable cassettes because they contain simple or composite materials that are difficult to destroy or recycle, such as cardboard laminated via complex adhesives with aluminium foil, plastic parts in PVC, metal staples, etc., so that the photographic industry is now promoting the use of lighttightly packaged rolls of light-sensitive material suitable for daylight loading. Thus, the fresh rolls of photographic material are wrapped by their manufacture in such a way that they still fit in the original dedicated cassettes, while leaving a leader projecting from the dispenser slot of the cassette. This leader allows withdrawal by hand of the lighttight wrapper of the filmroll from the cassette and next pulling the leading end of the film through the dispensing slot of the cassette so that the latter can be introduced in a usual way in the phototypesetting apparatus.
A cassette which bears some analogy with the cassette according to the present invention is disclosed in U.S. Pat. No. 5,053,597. This cassette too is made entirely of plastics and comprises a housing with two parts hingedly connected together. It has, however, the disadvantages that it is made by injection moulding so that each film roll format requires a separate mould, and that the hinge is composed of a plurality of distinct sub-elements causing a further increase of the costprice of the mould.
Another plastics cassette is disclosed in EP-A1-0 325 308. The housing of the cassette is made by extrusion moulding and has an integral hinge from an elastic material, co-extruded with the rest of the housing. The side caps or end covers are permanently fitted to the cassette by the manufacturer of the photographic material once the cassette has been loaded with a roll of film. The described cassettes are not reloadable and are thus in conflict with nowadays environmental insights.